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Screening the microwave-assisted extraction of hydrocolloids from Ocimum basilicum L. seeds as a novel extraction technique compared with conventional heating-stirring extraction

Keisandokht, Shima, Haddad, Nour, Gariepy, Yvan, Orsat, Valérie
Food hydrocolloids 2018 v.74 pp. 11-22
Fourier transform infrared spectroscopy, Ocimum basilicum, absorbance, basil, hydrocolloids, microwave treatment, moieties, pH, rheology, rheometers, screening, seeds, viscosity
Microwave assisted extraction (MAE) of basil seed hydrocolloid (BSH) was performed and compared with conventional heating-stirring extraction (CHSE) through a full factorial screening design with two levels considered for each of the variables. The mean yield value for the MAE was significantly higher compared with CHSE (10.46% and 6.17% respectively). Also, the mean yield value for the low pH (pH 4) extracted BSH was higher compared with the high pH (pH 11) extracted hydrocolloid in both MAE (11.39 and 9.52%) and CHSE (6.78 and 5.55%) methods. The rheology analysis of the extracted BSH, with AR 2000 rheometer, showed significant shear-thinning behavior for both MAE and CHSE extracts with higher apparent viscosity reached for the low pH MAE (258.2 mPa s) compared with the high pH MAE (252.9 mPa s), low pH CHSE (206 mPa.s), and high pH CHSE (204.6 mPa s). The dynamic shear rheology measurements of BSH showed G′ > G″ phenomenon for both MAE and CHSE for all the studied BSH solution concentrations (0.5, 1, and 2%). The latter attributed to the elastic property of the gum solutions which is described by a relatively strong interconnected network developed within the molecules in the solution matrix. The FT-IR analysis of BSH extracted through MAE and CHSE displayed similarity in terms of functional groups with higher absorbance intensities obtained for the BSH extracted through MAE.